2,347 research outputs found
Beltway: Getting Around Garbage Collection Gridlock
We present the design and implementation of a new garbage collection framework that significantly generalizes existing copying collectors. The Beltway framework exploits and separates object age and incrementality. It groups objects in one or more increments on queues called belts, collects belts independently, and collects increments on a belt in first-in-first-out order. We show that Beltway configurations, selected by command line options, act and perform the same as semi-space, generational, and older-first collectors, and encompass all previous copying collectors of which we are aware. The increasing reliance on garbage collected languages such as Java requires that the collector perform well. We show that the generality of Beltway enables us to design and implement new collectors that are robust to variations in heap size and improve total execution time over the best generational copying collectors of which we are aware by up to 40%, and on average by 5 to 10%, for small to moderate heap sizes. New garbage collection algorithms are rare, and yet we define not just one, but a new family of collectors that subsumes previous work. This generality enables us to explore a larger design space and build better collectors
Higher Curvature Gravity from Entanglement in Conformal Field Theories
By generalizing different recent works to the context of higher curvature
gravity, we provide a unifying framework for three related results: (i) If an
asymptotically AdS spacetime computes the entanglement entropies of ball-shaped
regions in a CFT using a generalized Ryu-Takayanagi formula up to second order
in state deformations around the vacuum, then the spacetime satisfies the
correct gravitational equations of motion up to second order around AdS; (ii)
The holographic dual of entanglement entropy in higher curvature theories of
gravity is given by Wald entropy plus a particular correction term involving
extrinsic curvatures; (iii) CFT relative entropy is dual to gravitational
canonical energy (also in higher curvature theories of gravity). Especially for
the second point, our novel derivation of this previously known statement does
not involve the Euclidean replica trick.Comment: 12 pages, 2 figure
Environmental Defense Center v. Bureau of Ocean Energy Management
The United States Court of Appeals for the Ninth Circuit upheld the district courtās grants of summary judgment and injunctive relief against BOEM for violating the ESA and CZMA. The Ninth Circuit found BOEM violated NEPA, CZMA, and the APA by failing to adequately consider the environmental impacts of well stimulation treatments. The Ninth Circuit also reversed the lower courtās grant of summary judgment against the Environmental Defense Center for their NEPA claims
Quantum process tomography via completely positive and trace-preserving projection
We present an algorithm for projecting superoperators onto the set of
completely positive, trace-preserving maps. When combined with gradient descent
of a cost function, the procedure results in an algorithm for quantum process
tomography: finding the quantum process that best fits a set of sufficient
observations. We compare the performance of our algorithm to the diluted
iterative algorithm as well as second-order solvers interfaced with the popular
CVX package for MATLAB, and find it to be significantly faster and more
accurate while guaranteeing a physical estimate.Comment: 13pp, 8 fig
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